so i know how to do all the light graffiti and that to time the flash for the second curtain, but what i dont know is how to light the subjects face/body and only that. and have a completley black background. do u just have to do this in photoshop?

Here's what I would do. Put the Speedlite on a light stand and aim the head at the subject. Put a snoot or a grid snoot on the flashhead. Set power to say 1/16 to start with and adjust power accordingly after test shots (do tests prior to light painting session). Connect the wireless radio receiver trigger but hold the transmitter in your hand. Now while the camera is doing it's long exposure, hit the test button on the wireless radio trigger transmitter to fire the Speedlite on the light stand. Check the DSLR LCD to see if you're getting what you want.

Oh, I see...you could use a LED flashlight and have someone shine it on you for a given amount of time. A friend of mine tried it (he's into light painting) and the picture came out pretty good. I don't recall how long the exposure was or how long the LED flashlight was lighting his subject. I do know the LED flashlight wasn't on for the entire exposure.